Climate Change May Have Caused The Rise And Fall Of Several Civilizations

The climate is a big topic in San Francisco this week at the
American Geophysical Union’s fall meeting.

One part of that effort is looking to the past to understand how
changes in temperature and precipitation affected the rise and
fall of civilizations.

This morning I met one of the researchers involved in an effort
to determine any connections between the rise of the Mongol
empire – which at one time controlled more contiguous land than
any other in history – and climate factors.

Amy Hessl from West Virginia University, working with two other
researchers, has developed what she stressed was a hypothesis
that wet conditions in the 1200s allowed the Mongols, led by
Chinggis Khan (usually known to Americans as Genghis Khan) to
come to power. They need to do much more work to verify the idea,
she said.

The researchers looked at tree ring data from pine and larch
trees. The growth rings indicated that trees grew well in the
13th century.

“Both species show that conditions were wet in the 1200s, when
Chengiss Khan came to power,” said Hessl.

The way these conditions may have helped the Mongols are as
follows, Hessl suggested. The Mongols were nomads, who relied
heavily on livestock such as sheep or goats, and also on horses.
When the grasslands were well-nourished by rains, so were those
animals, which helped the Mongols with both their needs for
transportation and for food.

This is just the beginning of the researchers’ effort to
investigate this connection, Hessl said. “This is an intriguing
idea.”

In addition to making further investigations of the regional
climate during the expansion of the empire, future efforts will
investigate previous empires that originated in the same area
hundreds of years earlier.

This has garnered some previous media coverage, such as this
interview with
LiveScience.

There are many other researchers looking at how climate changes
led to the rise or fall of other civilizations. Yesterday, at a
press conference, two researchers described their research into
ancient Middle Eastern and South Asian societies, and the effect
of droughts they suffered.

Sebastian Breitbach of EPH Zurich discussed the climate and its
potential impact on Harappan culture, which was active in
modern-day India between about 5,000 and 3,500 years ago, as well
as a Persian civilization from the areas we now call Afghanistan
and Pakistan. As it is today in those areas, water was scarce at
that time. The societies had advanced irrigation systems, but in
times of great drought, they might not have been sufficient.

Breitbach gathers climate data from caves, which can provide good
information, but actually collecting the data is difficult, he
said, because many of the places where he might go to collect
samples are either protected, hard to reach or otherwise
impractical.

At the same press conference Matthew Konfirst, from the Ohio
State University, discussed the disappearance of the
Sumerian civilization and their language. In the cradle of
civilization in the Middle East — about 4,000 years ago — there
were two major language families, he said.

One eventually became Hebrew and Arabic and other familiar
languages, whereas the other family, Sumerian, stopped evolving
when that civilization collapsed, a linguistic dead end. That
collapse coincided with a drought that lasted hundreds of years,
he said.

It’s been fascinating to learn about how scientists are beginning
to find data to verify why different civilizations succeeded or
collapsed.

Konfirst summed up these efforts near the end of the press
conference: “Climate itself is a fabric that society builds
itself upon… There are a number of factors that come together to
form what we call history."